Nvidia 8600 GT problems

[CPUskills101]

Some Nvidia cards are known to cause black screens and no signal to monitors.
My card in particular gets random lose signal to monitor when run graphics intensive programs like games.

Here are my CPU specs:

Operating System
MS Windows XP Professional 32-bit SP3
CPU
Intel Pentium 4 550
Prescott 90nm Technology
RAM
2.00 GB Dual-Channel DDR2 @ 267MHz (4-4-4-12)
Motherboard
ASUSTeK Computer INC. P5AD2-E-Premium (Socket 775) 70 °C
Graphics
Default Monitor (1280x1024@60Hz)
512MB GeForce 8600 GT (PNY) 49 °C
Hard Drives
313GB Western Digital WDC WD3200AAKS-22L6A0 (SATA) 22 °C
Optical Drives
TDK DVDRW880N
Audio
C-Media High Definition Audio Device

anyone have any idea what could be the error?
is it software based or hardware?

[Velo:Sity]

Is one of the motherboard sensors really showing 70 degrees temperature? If you are running latest games that might be a bit too much strain for these components. Try logging all available temperatures while playing to see if any are too high.